The present invention is related to disc type brake shoes for railway vehicles and particularly to a segmented disc brake shoe assembly.
Presently, disc brake shoe linings are molded and machined into a block of composition friction material having a configuration, as shown in FIG. 1, corresponding generally to a metal backing plate such as shown in FIG. 2. The molded block of friction material and the backing plate are provided with a multitude of conforming holes through which rivets are inserted to secure the brake shoe lining to the backing plate. In order to support the brake shoe lining under heavy brake loads without any appreciable bending, which could cause the lining to crack, the backing plate is formed from relatively thick gage, high strength steel and thus represents a costly item of a brake shoe. Consequently, it is desirable to reclaim these backing plates for re-use, which requires removal of the multitude of securing rivets in order to dis-assemble the worn brake shoe lining from its backing plate. This, in itself, is an expensive operation.
Moreover, the multitude of rivet holes in the brake lining reduce the strength and wearability factor of the composition friction material of the brake shoe lining, while the cost of machining the friction material as required by the specific backing plate design, and the expense of securing the replacement brake shoe lining to the backing plate by means of rivets still exists.
State-of-the-art technology makes it possible to chemically bond the composition friction brake lining to the metal backing plate to eliminate the above-discussed disadvantages of rivets, but reclaiming the backing plate from worn brake shoes for re-use still entails a difficult, time-consuming operation to remove the friction material and to clean the backing plate sufficiently, as required for bonding the new brake shoe material thereto during the re-lining process. In addition, the thick gage backing plate with worn linings must be transported from the customer to the brake lining manufacturing facility for relining and subsequent delivery back to the customer. These expenses are even further exacerbated where different thickness backing plates must be stocked to accommodate various wear states of the brake disc, where brake units without automatic slack adjusting means are employed.